Stock inlet system for a paper making machine including converging settling ducts

ABSTRACT

Stock is fed to a discharge chamber and discharge slice from a stock inlet chamber or manifold by first passing through multiple manifold pipes which convey the stock to a chamber where the stock is mixed and fiber clumps are broken up. The stock then is passed through multiple settling ducts which may have circular, rectangular or pentagonal cross-sectional shapes to the discharge chamber, the ducts being substantially parallel when viewed from above, but having portions immediately upstream of the discharge chamber converging with one another in the vertical direction when viewed from the side. Each duct has a constant crosssectional shape, and the convergence of the multiple ducts into the discharge chamber is such that each duct is separated from each other by a thin cutting edge.

Unite Statesatent 1191 Schiel 1 Oct. 36, 1973 STOCK INLET SYSTEM FOR A PAPER 3,373,080 3/1968 Appel et al. 162/343 MAKING MACEINE ENCLUDING 3,328,236 6/1967 Burgess et a1 162/343 X CONVERGING SETTLING DUCTS Christain Schiel, Heidenheim-Schnaitheim, Germany Assignee: J. M. Voith GmhH, l-leidenheim (Brenz), Germany Filed: Feb. 16, 1971 Appl. No.: 115,241

Inventor:

Foreign Application Priority Data Feb. 18, 1970 Germany P 20 07 308.9 July 29, 1970 Germany P 20 37 539.7

References Cited UNITED STATES PATENTS 3 1972 Appel 162/343 9 1971 Hill et al. 11 1970 Springuel et al 162/343 x Primary Examine'r-S. Leon Bashore Assistant ExaminerRichard H. Tushin Attorney-Melvin A. Crosby [5 7 ABSTRACT Stock is fed to a discharge chamber and discharge slice from a stock inlet chamber or manifold by first passing through multiple manifold pipes which convey the stock to a chamber where the stock is mixed and fiber clumps are broken up. The stock then is passed through multiple settling ducts which may have circular, rectangular or pentagonal cross-sectional shapes to the discharge chamber, the ducts being substantially parallel when viewed from above, but having portions immediately upstream of the discharge chamber converging with one another in the vertical direction when viewed from the side. Each duct has a constant cross-sectional shape, and the convergence of the multiple ducts into the discharge chamber is such that each duct is separated from each other by a thin cutting edge.

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Y INVENTOR. CHRISTIAN 5CHIEL STOCK INLET SYSTEM FOR A PAPER MAKING MACHINE INCLUDING CONVERGING SETTLING DUCTS The present invention relates to paper making machines and, in particular, to a stock inlet system for a paper making machine having a stock supply chamber extending the width of the machine and having disposed downstream therefrom a plurality of adjacently and superjacently disposed ducts for settling, or quieting, the flow and extending into a discharge chamber, also extending the width of the machine, said discharge duct converging in the direction of stock flow terminating in a discharge nozzle.

A stock inlet system generally of the type referred to is disclosed in U.S. Pat. No. 3,328,236. In the stock inlet system of the patent, the settling ducts are formed by pipes which connect directly to the stock supply chest, and which extends the width of the machine. In the arrangement of the patent, all the pipes extend parallel to each other along a first section adjacent the stock supply chest, followed by a second section along which the pipes are parallel to each other as seen in plan view but converge as seen in a side elevation, followed, finally, by a third section along which the pipes extend parallel to each other both in plan view as well as in side elevation.

The construction of the patent referred to offers the advantage of compactness but supplies a paper web in which the transparency and structure is not always satisfactory. This is due to the fact that the flow crosssection widens substantially and suddenly when the pulp stream from the pipes enters the discharge chamber and merges therein, thus causing an entry surge and eddies in the current at a flow velocity which fluctuates over the width of the web and also with respect to time and, in addition, has transverse components.

In order to adapt the flow cross-section of the pipes in the exit zone at the discharge chamber as closely as possible to the cross section of the discharge chamber, the pipes in the exit zone are disposed as closely adja cent each other as possible. However, owing to a minimum. wall thickness, which is necessary for the pipes, the pipes cannot be brought so near to eachother at will so that the problem can be solved in this manner. To settle, or quiet, the flow it would also be possible to extend the discharge duct in the direction of flow, but such an extension, to be effective, would have to be so substantial as to prevent the stock inlet system being constructed in a compact manner. An increase in the number of pipes and a simultaneous reduction of the cross-sectional area of each individual pipe would also reduce the formation of eddies, but experience has shown that narrow pipes become easily blocked and batches or clumps of fibers can form at the inlet ends thereof, and the formation of such batches would have to be prevented by agitators which do not always operate reliably.

The prior art also discloses a stock inlet system (French Pat. No. 1,560,071) in which ducts are provided which converge to their ends in the flow direction, and as seen in one side elevation, but wherein each individual duct extends over the entire machine width so that eddies may once again be formed in each individual duct. Moreover, a discharge chamber is absent in this stock inlet system and, instead, all ducts terminate immediately at the stock discharge nozzle.

With the foregoing in mind, an object of the present invention is the provision of a stock inlet arrangement for a paper making machine which overcomes the drawbacks of prior art machines.

A further object of the present invention is the provision of a stock inlet arrangement for a paper making machine which is compact but which produces superior results.

A further object of the present invention is the provision of a stock inlet arrangement for a paper making machine which provides for the production of a sheet of greater uniformity and better transparency than has been provided heretofore.

The exact nature of the present invention will become more apparent upon reference to the following detailed specification taken together with the accompanying drawings in which:

FIG. 1 is a vertical longitudinal section taken through a stock inlet system according to the present invention;

FIG. 2 is a plan view of the stock inlet system according to FIG. 1;

FIGS. 3, 4a, 4b, 5a, 5b, 5c and 6a, 6b, 6c, are crosssections through the stock inlet system according to FIG. I and are indicated by section lines III-III, lV-IV, VV, and VI-Vl on FIG. 1;

FIG. 7 is a vertical longitudinal section similar to FIG. 1, showing a further stock inlet system according to the present invention;

FIGS. 8a, 8b, 8c are cross-sections through the stock inlet system according to FIG. 7 and are indicated by section line VIIIVIII on FIG. 7;

FIG. 9 is a vertical longitudinal section similar to FIGS. 1 and 7, showing a further stock inlet system; and

FIGS. 10 and 11 are cross-sections through the stock inlet system according to FIG. 9 and are indicated by section lines XX and Xl-Xl on FIG. 9.

BRIEF SUMMARY OF THE INVENTION The present invention has a stock inlet chamber extending the full width of the machine in the transverse direction while ducts lead therefrom in the direction of flow of the stock. The ducts are in side by side and superposed relation and converge in the direction of flow and discharge into a discharge chamber which extends the width of the machine and which terminates in a discharge nozzle. The ducts settle, or quiet, the flow and a. paper web of improved uniformity and transparency is produced.

GENERAL DISCUSSION OF THE INVENTION According to the present invention, the problems referred to are solved by arranging the ducts so as to converge toward the discharge duct in their exit zone as seen in side elevation, but extending in parallel to each other as seen in plan. If the ducts are formed from pipes, as in the aforementioned known stock inlet systern, it is possible for these pipes to have a substantial wall thickness over the greater part of their length and to have a continuously diminishing wall thickness only in the last zone extending to the exit into the discharge chamber; the individual wall thickness may, in fact, be reduced to such an extent that only knife edge-like members remain between ducts at the discharge chamber. In this way, it is possible for the ratio of crosssectional area of the ducts immediately upstream of the exit plane and relative to the cross-sectional area of the discharge chamber immediately downstream of the exit plane to approach unity so that the cross-sectional area available to the suspension stream is not enlarged or, at most, is only slightly enlarged when passing through the exit plane. The previously mentioned entry surge is thus minimized, or completely eliminated, so that eddies or flow fluctuations occur only slightly or not at all and the quality of the paper web is thus improved.

The previously mentioned convergence of the ducts need be provided only in the last zone upstream of the position at which they merge into the discharge chamber but it is also possible for such convergence to exist over the entire duct length from the stock inlet chamber to the discharge chamber. Furthermore, it is of no consequence for the success of the invention whether the aforementioned supply duct of machine width is disposed upstream of the ducts either directly or only indirectly.

An advantageous embodiment of the subject of the invention may be obtained in that the pipes of a multipipe manifold leading from the stock inlet chamber terminate at a distance from the settling ducts and are orientated towards the space between at least two settling ducts so that a mixing chamber precedes the entrance ends of the ducts. This prevents the stock discharged from one manifold pipe reaching only a single settling duct.

In a further embodiment of the invention the ducts are formed of solid material, either by working of the ducts from the solid by drilling, milling, or the like, or by casting. To this end, the ducts are surrounded on all sides by material, resulting in a very stable construction, in contrast to a construction obtained by forming ducts from pipes. The ducts need not, of course, be formed from a single solid block (for example, stainless steel), but it may be appropriate, for reasons of cleaning of the ducts, necessary from time to time, or it may be essential for manufacturing reasons for such ducts to be assembled from several parts.

In functional terms, the'best result is obtained with a rectangular or hexagonal duct section. In the last mentioned case, the ducts are associated with each other in honeycomb fashion. A pentagonal section for the individual ducts is also possible if two rows of ducts are superjacently disposed. The thickness of material for the aforementioned sections between the individual ducts may be uniform throughout, irrespective of whether the ducts are formed from sheet metal tubes or from solid material. This is not the case for circular duct sections but such a section can be produced more readily.

A particularly advantageous embodiment of the subject of the invention is obtained when the walls of the discharge chamber, when viewed from the side, converge substantially at the same angle as the settling ducts, or the outer settling ducts, if more than two of these are provided, at least in the same way as in the zone disposed immediately upstream of the discharge chamber. This ensures that, on emerging from the ducts, the stock flow continues without any deflection, or with only slight deflection, into the discharge chamber and any detachments or eddies are avoided in the zone of the aforementioned wall. For the. same reason it is also advantageous for the walls of the discharge chamber to merge continuously into those of the exit slot.

DETAILED DESCRIPTION OF THE INVENTION The stock inlet system illustrated in FIGS. 1 and 2 has a stock inlet chamber in the form of a transverse pipe, one end of which has an inlet 2 and the other end a discharge 4 with regulating valve 3 and to which a plurality of manifold pipes 5 are connected. After flowing through the manifold pipes S, the paper pulp suspension, or stock, flows through a connecting plate 5a and through a mixing chamber 6 of machine width and thereupon through a plurality of settling ducts 7.

Ducts 7 are disposed in two superjacent rows to flow into a discharge chamber 8 of machine width, said chamber being restricted at approximately half its length and terminating in a slit discharge nozzle 9. The mixing chamber 6, the settling ducts 7 and the discharge chamber 8 are machined from the solid, namely, from several parts of solid material comprising a lower plate 10, an upper plate 11, a core 12, a lower lip 13 and an upper lip 14. It has been found advantageous for the cross-section of the settling ducts 7 to be smaller than that of the manifold pipes 5.

The cross sections illustrated in FIGS. 3, 4a, 4b, 5a, 5b, Sc, 6a, 6b, and 6c illustrate some of the many different possible duct configurations and arrangements.

The manifold pipes 5 are usually of circular crosssection as shown in FIG. 3. By contrast, the settling ducts 7 may have different shapes, that is to say, they may be circular as shown in FIGS. 4a, 4b, 5c and 6c, or rectangular as shown in FIGS. 5a and 6a, or pentagonal, as shown in FIGS. 5b and 6b. The differently shaped ducts, however, retain their cross-sectional shape throughout their length. Furthermore, the settling ducts 7 may be disposed differently relative to the manifold pipes 5. FIGS. 6a and 6b disclose that the ducts 7 in the exit plane are separated from each other only by thin cutting edges 14, 24, formed by the core 12, while somewhat more material 34 remains between the circular ducts 7 illustrated in FIG. 60. This is achieved by virtue of the fact that, as seen in plan view, the ducts extend in parallel but are closely adjacent to each other over their entire length and that, as seen in a side view, illustrated in FIG. 1, they converge along the general axial orientation of the machine.

The stock inlet system illustrated in FIG. 7 Compared with that of FIG. I has three superjacently disposed rows of settling ducts 17a, b. These are connected directly to manifold pipes 15 of a pipe manifold 10, without the interposition of an eddy, or mixing, chamber and, therefore, represent an extension of the ducts. The settling ducts are, in each case, assembled from a first section 17a and a second section 1712. The first sections 17a of the three rows extend in parallel to each other, while the sections 17b converge relative to each other. The cross-section of the second sections 17b are expanded relative to the first sections. A discharge chamchamber 16 of machine width, each of which is connected to a row of settling ducts 27. The said settling ducts extend initially in parallel to each other and subsequently converge relative to each other in the flow direction as far as their exit into the discharge chamber 28. The mixing chambers 16, the settling ducts 27 and the discharge chamber 28, with the exit slit 29, are worked from solid parts and are separated from each other by a core 32. The walls of the discharge chamber 28, converge in the flow direction at the same angle as the settling ducts 27. To this end, the discharge chamber 28 narrows towards the exit slit 29 and merges continuously therewith. The walls of the discharge chamber 18 of FIG. 7 may also converge at the same angle as the settling ducts 17b of the two outer rows. To this end, and as seen in a side view, the center lines of the settling ducts of all rows extend at least approximately through a single point.

In the embodiments illustrated in FIGS. 1 and 9, the pipes 5 or 25 of the multi-pipe manifold leading from the stock inlet chamber terminate at a distance from the downstream disposed settling ducts 7 and 27, respectively, the appropriate mixing chamber 6, 16, being interposed, the pipes of the manifold being orientated towards the space between the settling ducts as shown in dot-dash outline in FIGS. 4a and 4b.

Modifications may be made within the scope of the appended claims.

What is claimed is:

1. In a stock inlet system for a paper making machine; a substantially horizontal stock inlet chamber extending substantially the full width of the machine, a substantially horizontal discharge chamber also extending substantially the full width of the machine and spaced in the horizontal direction from said stock inlet chamber and in the direction of stock flow, said discharge chamber comprising a slit-like discharge nozzle on the side thereof opposite said stock inlet chamber, stock conveying means for conveying stock from said inlet chamber to said discharge chamber including a plurality of pipes forming a multipipe manifold connected at the upstream end to said stock inlet chamber and leading therefrom toward said discharge chamber, means forming a mixing chamber extending substantially the full width of the machine and connected on the upstream side to the downstream end of said multipipe manifold, means forming ducts of constant crosssectional shape arranged in laterally and vertically distributed relation, said ducts being substantially parallel when viewed from above and being connected at the upstream ends to the downstream side of said mixing chamber, the downstream ends of said ducts being connected to said discharge chamber, the upstream ends of said ducts beind distributed over the width and height of said mixing chamber, said ducts including at least a portion immediately upstream of said discharge chamber converging with one another in the vertical direction toward said discharge chamber, the downstream ends of said ducts being distributed along the width of said discharge chamber and confined within the height of said discharge chamber.

2. A stock inlet system according to claim 1 in which said ducts comprise a plurality of spaced ducts and each pipe of said manifold enters the upstream side of said mixing chamber in a region such that the flow therefrom is directed toward the space between adjacent ones of said ducts on the downstream side of said mixing chamber.

3. A stock inlet system according to claim 1 in which said discharge chamber comprises upper and lower walls and at least that portion of the discharge chamber adjacent the downstream ends of said ducts converging inthe direction of stock'flow at substantially the same angle as said portion of said ducts converge.

4. A stock inlet system according to claim 3 in which said discharge nozzle has upper and lower walls merging with said upper and lower walls of said discharge chamber.

5. A stock inlet system according to claim 1 in which said ducts are formed in solid material.

6. A stock inlet system according to claim 1 in which each said duct includes a first region upstream from the said portion thereof which is smaller in cross-sectional area than said portion. 

1. In a stock inlet system for a paper making machine; a substantially horizontal stock inlet chamber extending substantially the full width of the machine, a substantially horizontal discharge chamber also extending substantially the full width of the machine and spaced in the horizontal direction from said stock inlet chamber and in the direction of stock flow, said discharge chamber comprising a slit-like discharge nozzle on the side thereof opposite said stock inlet chamber, stock conveying means for conveying stock from said inlet chamber to said discharge chamber including a plurality of pipes forming a multipipe manifold connected at the upstream end to said stock inlet chamber and leading therefrom toward said discharge chamber, means forming a mixing chamber extending substantially the full width of the machine and connected on the upstream side to the downstream end of said multipipe manifold, means forming ducts of constant cross-sectional shape arranged in laterally and vertically distributed relation, said ducts being substantially parallel when viewed from above and being connected at the upstream ends to the downstream side of said mixing chamber, the downstream ends of said ducts being connected to said discharge chamber, the upstream ends of said ducts beind distributed over the width and height of said mixing chamber, said ducts including at least a portion immediately upstream of said discharge chamber converging with one another in the vertical direction toward said discharge chamber, the downstream ends of said ducts being distributed along the width of said discharge chamber and confined within the height of said discharge chamber.
 2. A stock inlet system according to claim 1 in which said ducts comprise a plurality of spaced ducts and each pipe of said manifold enters the upstream side of said mixing chamber in a region such that the flow therefrom is directed toward the space between adjacent ones of said ducts on the downstream side of said mixing chamber.
 3. A stock inlet system according to claim 1 in which said discharge chamber comprises upper and lower walls and at least that portion of the discharge chamber adjacent the downstream ends of said ducts converging in the direction of stock flow at substantially the same angle as said portion of said ducts converge.
 4. A stock inlet system according to claim 3 in which said discharge nozzle has upper and lower walls merging with said upper and lower walls of said discharge chamber.
 5. A stock inlet system according to claim 1 in which said ducts are formed in solid material.
 6. A stock inlet system according to claim 1 in which each said duct includes a first region upstream from the said portion thereof which is smaller in cross-sectional area than said portion. 